Someone who has a chip on their shoulder is angry all the time. They feel that they have been wronged by the world, so they are always ready for a fight. They are easily offended because they feel that they have been treated unfairly by others, or perhaps they feel inferior. They expect trouble, so they are always ready for it.

It can also mean that the person has a grievance about something. Something bad has happened to them, and they might believe it was someone else’s fault. They are constantly so angry about it that it affects their behaviour. In the person’s mind, they’re showing how tough they are.

*Because this expression is used to describe someone and because it uses the verb ‘have,’ you can also use ‘have got’. You can also add adjectives to describe the size of the chip:

I can’t stand working with Bill; he’s got such a massive chip on his shoulder. He’s so unpleasant.

. . . Keira Knightley has admitted that forsaking university in favour of a film career has left her with a “chip on her shoulder” over her lack of education. . . . [She] now battles to prove to herself – and those around her – that she has brains.
– from The Telegrah (U.K.)

Success never made that chip on his shoulder go away. (about Roger Ailes, Fox News Chief )
– from The New York Times

James “Sawyer” Ford [a character on the TV show LOST] started as the classic rogue with a shady past who parades around with a constant chip on his shoulder.
– from IGN.com

Origin of the expression:
This expression originated in the U.S. According to the Oxford English Dictionary, the first recorded use was in 1830 in the Long Island Telegraph newspaper: When two churlish boys were determined to fight, a chip would be placed on the shoulder of one, and the other demanded to knock it off at his peril. In this case a chip is a small piece of wood. A young boy who was angry about something and determined to fight would place a small chip of wood on his shoulder and challenge another person to knock it off his shoulder. When the chip was knocked off, it meant the opponent was ready and the fight would begin. It was his way of showing everyone how tough he was. Later, in 1855, the actual expression ‘a chip on your shoulder’ appeared in print in the Weekly Oregonian newspaper: Leland, in his last issue, struts out with a chip on his shoulder, and dares Bush to knock it off. Nowadays, the chip is figurative – there’s no physical chip of wood on someone’s shoulder, he/she just acts like there is!

Do you know someone who has a chip on their shoulder?